This invention is directed toward the field of semiconductor microstructures.
As an example, one method of construction of semiconductor devices involved the formation of an epitaxial layer of N type silicon on a first layer of P type silicon. In one case, a portion of the first layer was then etched away, leaving a support rim and a diaphragm which formed a pressure transducer. Another possible construction involved formation of a cantilever beam from the N type layer which acted as an accelerometer.
In order to improve the linearity and accuracy of these devices, it was desirable to attach bosses to the diaphragm of the pressure transducer or the cantilever beam of the accelerometer. A problem existed in that the boss thicknesses could not be tightly controlled since the bosses were formed by using a bottom side etch or a top and bottom etch. Another problem existed in that one or more dimensions of the boss needed to be as small as possible to reduce parasitic effects in the structure. The etching process is difficult to control with accuracy, thus bosses of varying dimensions were often produced.
In addition, it was occasionally desirable to produce other microstructures within a semiconductor device. Examples of such other microstructures are holes and top and bottom side notches.